What makes this lasagna healthier than most is the lack of meat, béchamel, and the more conservative use of cheese. The recipe only uses a pound and change, which doesn't amount to a crazy portion if you can manage to not inhale the whole pan (which might provide to be difficult). It's called skillet lasagna because it's made in a large cast-iron pan instead of the usual casserole dish. You can easily use whatever pan you like, and you can also substitute baby spinach for the arugula.
Preheat the oven to 350 degrees.
Heat the olive oil in a large ovenproof nonstick skillet over a high flame. Sauté the zucchini and shallot until tender, about 5 minutes. Add the arugula and basil and continue to sauté until wilted, about 2 minutes. Season well with salt and papper. Set aside.
Ladle ½ cup of the sauce into the bottom of the skillet and smooth to form an even layer. Arrange 4 noodles on top of the sauce — you might have to break the side noodles to fit, depending on the size of your skillet. Spoon half the filling on top of the noodles and spread to form an even layer. Sprinkle half the fontina on top of the vegetables, followed by half the ricotta. Repeat with another ½ cup sauce, noodles, the rest of the filling, fontina, and ricotta. Top with the remaining noodles and cover with the remaining sauce. Sprinkle the top with the mozzarella.
Cover the pan tightly with foil and bake in the oven for 1 hour, until the noodles are cooked through and the cheese is very melted.
Serve immediately alongside a simple salad.